Unique communication of coconut crab

During mating, coconut crabs - the largest terrestrial invertebrates in the world, create cracking sounds to interact.

Coconut crabs communicate with each other by the sound of snap . The scientists found their fluttering sounds were much more varied than expected, including a series of signals that indicate the level of complex communication, according to research published in Zoology.

Coconut crabs live on islands in the Pacific Ocean.(Photo: Live Science).

Weighing 4 kg and having a stride longer than one meter, the coconut crab (Birgus latro) is the largest crustacean and the world's largest terrestrial invertebrate. They used to live on the islands of the Indo-Pacific region but were hunted to extinction in many places.

Previously, researchers did not know how or why coconut crabs made knocking sounds. In the new study, they took X-rays of the flattering coconut crabs to discover the source of the sound. They also digitally record the interaction between males and females to see if the flicking is even more associated with mating behavior.

In the experiment, male and female coconut crabs flicked before, during and after mating. The sound they make differs at each stage. The results of the X-rays revealed the crabs to communicate by vibrating the water fan scales , the appendages that help draw air into the lungs. When vibrated, this part hit the hard shell under the crab gills, making a knock. By changing the vibration speed, coconut crabs can produce a variety of sounds in frequency and tempo.

In addition to coconut crabs, the only other crustacean species that can make a sound with a fan fan is the underwater lobster (Procambarus clarkii) . Although the study recorded only the interaction between male and female crabs in heat, the animal also used flapping sounds in many activities other than mating, according to scientists at the Okiawa Churashima Conservation Center.

1. See the largest crab on the land clear the body of a . pig
2. Giant crab monster, climbing, robbing fast as lightning